1. Field
The present invention relates to a tire for an aeroplane and, in particular, to the crown of an aeroplane tire.
2. Description of Related Art
Aeroplane manufacturers are constantly concerned with passenger safety and, therefore, with reducing the risks of failure of their craft. Of the failure modes considered, the partial or complete loss of the tread of a tire with which an aircraft landing gear is equipped, is a critical failure mode that occurs during aeroplane takeoff or landing phases.
This failure mode occurs, in particular, when the tire runs over a blunt object that might by chance be present on the runway. Bearing in mind the harsh conditions of use of an aeroplane tire, which are characterized by a high inflation pressure, a high static loading and a high speed, the tread of the tire running over the blunt object causes damage to the tread which generally results in the cutting of the tread and then in pieces of tread of varying geometric dimensions and mass being thrown up.
The pieces of tread may then either strike the structures of the aeroplane and lead to significant structural damage, because of the mechanical energy stored up by the said pieces, the higher the mass and speed at which the pieces are thrown up, the higher this mechanical energy is, or may enter the aeroplane engines and lead to problems with the operation of the said engines, if these engines are unable to absorb the pieces of tread because they are too great in size.
Reinforcing the structures of the aeroplane in order to withstand potential impacts, particularly those of pieces of tread, has been considered. However, for the same materials, this solution entails increasing the mass of the structure, something which is penalizing as far as aeroplane performance is concerned, which is why increasingly lightweight structural materials are being used. Mechanically strengthening the structure does not, however, solve the problem of pieces being thrown into the engines.
Devices affording protection against pieces of tread being thrown up have also been considered. Document WO 2010012913 describes a protective panel, the external surface of which comprises a composite material, and mounted, via deformable components, on a support connected to the structure of the aeroplane. The deformable components, fixed to several support stiffening components and perpendicular to the external surface of the protective panel are designed to buckle under the effect of impact by thrown up pieces of tread. Document WO 2010052447 describes a device that protects the engines of an aeroplane from thrown up tire tread debris. This device comprises a protective bar connected in a pivoting manner to the aeroplane main landing gear, the protective bar being able to move between a first and a second position. In the first position, the protective bar extends laterally across the mounted assembly consisting of the tire and of a wheel, to intercept possible paths of tread debris.
Another family of solutions describes devices that break up the tread with a view to minimizing the size of the pieces of tread and therefore minimizing impacts with the aeroplane. Document U.S. Pat. No. 7,669,798 describes break up means situated between the wheel and another part of the aeroplane and able to break up into several pieces the bit of tread which has become detached from the tire and is being thrown up towards the other part of the aeroplane. These break up means, such as a grating with blades able to cut up the material of the tread, are designed to disperse the said pieces.
The aforementioned protective or break up devices have the disadvantage of constituting additional structures, the additional masses of which are penalizing to the payload of the aeroplane.